I seem to be getting low fps in Gta IV with my new Gtx 460 card.
I get about 19fps avg ingame with GTX 460 but with 8600GT I was getting exactly the same....
I know Gta IV is a bad PC port but the difference between 8600GT and GTX 460 is BIG!
Even my GPU usage goes to 98% while playing gta IV
My CPU is Intel core 2 Duo e8400 @3.5GHz
Win 7, 32Bit
And my Ram is DDR2 800 1gb x 2
No need to buy another RAM.
I'm pretty sure you only see this problem with GTA 4 and not with the other games, your specs are good enough to play any games recently (don't count Crysis and GTA 4) with decent setting...